1. Field of the Invention
The present invention relates to composite piling and more particularly to a piling apparatus that includes a helical anchor lower end portion to which a plurality of connectable sections can be added, each section having a hollow interior through which a drive member can pass, and each section being joined to another section at a joint that has a specially shaped fitting to be engaged by an enlarged portion of the drive member.
2. General Background of the Invention
Piling must often be installed in locations wherein a full size pile driving rig simply cannot be positioned. For example, if a building is having a settlement problem, piling must necessarily be driven below the building to support its lower most structural aspect, such as the lowest concrete horizontal section or slab.
It has been known in the art to cut holes through the slab of a building and then install a screw type anchor or screw type anchor piling system, in order to add support to an existing piling system that is already under the building. Once these additional piling have been placed, structural ties can be made between the building itself and the new piling.
Because pile driving equipment is not able to fit into the ground floor of existing buildings, a screw threaded piling or helical anchor is employed because it can be installed using a hydraulic rotary drive, for example. Such drive units are commercially available.
High capacity pile driving equipment is large and cumbersome to operate in confined areas. Conventional pile driving equipment can cause stress and fatigue on adjacent structures from weight and vibration.
Piles are used to support structures, such as buildings, when the soil underlying the structure is too weak to support the structure. There are many techniques that may be used to place a pile. One technique is to cast the pile in place. In this technique, a hole is excavated in the place where the pile is needed and the hole is filled with cement. A problem with this technique is that in weak soils the hole tends to collapse. Therefore, expensive shoring is required. If the hole is more than about 4 to 5 feet deep then safety regulations typically require expensive shoring and other safety precautions to prevent workers from being trapped in the hole.
It is known to provide a cylindrical foundation support element having an open lower end and which may be rotatably driven into the ground by virtue of the provision of an integral annular helix permanently affixed to the outer surface of the lower end of the support. The helix has an earth penetrating edge, and in conjunction with the cylindrical foundation defines an opening through which soil is allowed to pass into the chamber formed by the cylindrical wall of the foundation support. The opposite end of the cylindrical foundation support is adapted for releasable locking engagement to a drive element, which is used to rotate the support in a given direction, thus driving the support into the ground to a desired depth.
Langenbach Jr., U.S. Pat. No. 4,678,373 discloses a method for supporting a structure in which a piling beating a footing structure is driven down into the ground by pressing from above with a large hydraulic ram anchored to the structure. The void cleared by the footing structure may optionally be filled by pumping concrete into the void through a channel inside the pile. The ram used to insert the Langenbach Jr. piling is large, heavy and expensive.
Another approach to placing piles is to insert a hollow form in the ground with the piles desired and then to fill the hollow form with fluid cement. Hollow forms may be driven into the ground by impact or screwed into the ground. This approach is cumbersome because the hollow forms are unwieldy and expensive. Examples of this approach are described in U.S. Pat. Nos. 2,326,872 and 2,926,500.
Helical pier systems, such as the CHANCE™ helical pier system available from the A. B. Chance Company of Centralia, Mo. U.S.A., provide an attractive alternative to the systems described above. As described in more detail below, the CHANCE helical pier system includes a helical screw mounted at the end of a shaft. The shaft is configured to draw the helical screw downwardly into a body of soil. The screw is screwed downwardly until the screw is seated in a region of soil sufficiently strong to support the weight which will be placed on the pier.
Many piling systems have been patented that include multiple sections, some of which are provided with screw anchors or helical anchors.
An early patent is the Gray patent entitled “metal Pile”, U.S. Pat. No. 415,037.
The Stevens U.S. Pat. No. 1,087,334, discloses and incased concrete piling.
A method for installing anchoring or supporting columns in situ is disclosed in U.S. Pat. No. 3,354,657.
A piling that includes a cylindrical foundation support drivable into ground with a removable helix is disclosed in the Holdeman U.S. Pat. No. 5,066,168.
The Watts U.S. Pat. No. 3,422,629 discloses a construction support system and method and apparatus for construction thereof. A helical member is part of the apparatus.
U.S. Pat. No. 3,864,923 discloses a method and means for providing a pile body in an earth situs, including driving casing into situs to define a cavity of required depth. An auger positioned within the casing is rotatable in screwing direction to remove earth from defined, cavity, and carries expansible cutter means rotatable with auger to enlarge cavity girth below inner end of casing. Earth removed from casing and cavity enlargement is replaced with different material, such as self-hardenable cement, to form pile body with load carrying enlargement at inner end of casing.
An earth auger is disclosed in U.S. Pat. No. 3,938,344 in which an auger shaft is provided with freely expansible and contractible rotary blades in such manner that said rotary blades may expand automatically when said auger shaft is rotated in the forward direction and may contract automatically when said auger shaft is rotated in the reverse direction. Also a method for driving piles and the like is disclosed which comprises the steps of positioning a pile or shoring adjacent to said auger shaft and above said blades, advancing said pile or the like into an earth bore excavated by said rotary blades, and filling said bore excavated by the rotary blades with mortar or the like.
The Turzillo U.S. Pat. No. 3,962,879 discloses a concrete pile or like concrete column formed in earth situs by rotating a continuous flight auger consisting or one or more sections into the earth to form a cavity of given depth; rotating the auger to remove augered earth from the cavity without removing the auger therefrom, and replacing the removed earth from the auger flights with fluid cement mortar, which hardens to form a column reinforced by the auger resultantly anchored in the same. A plurality of short auger sections may be connected together in succession during drilling to form a cavity of requisite depth by increments when low headroom conditions exist. A portion of the auger or a shaft portion without auger flighting thereon may also protrude above the earth situs for extension through water and the like and be filled with cementitious material which is allowed to harden. The method may also include first filling the auger shaft with the fluid mortar and allowing the same to harden in the shaft with a passage extending therethrough, and supplying more mortar through the passage to fill the cavity to form the column against backing of hardened mortar in the shaft.
The Vickars U.S. Pat. No. 5,707,180 discloses a method and apparatus for forming piles in situ. The '180 patent provides a method for making piles and apparatus for practicing the method. The piles may be used to support the foundation of a structure, such as a building. The method draws a soil displacer on a shaft down through a body of soil by turning a screw at the lower end of the shaft. The soil displacer forces soil out of a cylindrical region around the shaft. The cylindrical region is filled with grout to encapsulate and strengthen the shaft. The grout may be fed by gravity from a bath of grout around the shaft. The soil displacer has a diameter smaller than a diameter of the screw and may be a disk extending in a plane generally perpendicular to the shaft.